“Full darkness” isn’t even a real thing in nature.
And
It’s not like climbing into a cupboard, shutting the door, and sealing all the cracks with duct tape.
So I thought it was pretty clear I meant that to get "full darkness" where you really can't see, requires extra steps to intentionally make it happen. Just that for the vast majority of human evolution, we weren't really capable of it, and would have no reason to even try.